The state-of-the-art of tools utilized for driving nails, staples, joint-fasteners, drive rivets, spring pins and other fasteners has been limited to the use of a force, on a ram, where said force is either applied manually or via a pneumatically operated piston. As a result, for power tools, the force driving the ram is dependent, for a given pneumatic supply pressure, on the surface area of the piston, i.e., large driving forces require large piston areas and vice versa. A consequence of large piston areas is that they cause the physical size of the driving instrument to be large. A primary object of this invention is to provide an apparatus having a pneumatically driven hammer including a steel bar with a generally rectangular cross section and a head fastened crosswise at an end thereof, the hammer being operable to drive a ram.
The pivotally mounted hammer in said pneumatic power driving tool converts angular momentum into a resultant linear impulse on the ram and, thus, applies a linear impulse to the ram which is related to the hammer moment arm or radius. The hammer means thus permits a greatly increased ram power to be developed compared to driving instruments of comparable size utilizing a piston without said hammer means.
A factor limiting the velocity which the said hammer can attain is the air aperture velocity, that is, the velocity of the pressurized air being supplied behind the hammer. The velocity of the pressurized air depends in part upon the size of the aperture and the pressure of the air entering behind the said hammer. Therefore, another object of this invention is the provision of an air reservoir which minimizes the air pressure build up time required when air is released from an orifice and maintains a sufficient volume of air pressure for said hammer to draw upon when said power tool is triggered to drive.
The provisions of a pneumatic driving tool such as have been briefly outlined above and possessing the stated advantages constitute the principal and general objects of the invention.
Another object of this invention is the provision in said power driving tool of a rectangular form for said hammer which permits construction of said driving device so that maximum surface area is available for air pressure to generate a component perpendicular force on said hammer and, thus develop maximum force by the air on said hammer, resulting in an optimum power thrust on said hammer during the power driving cycle of the said invention.
Another object of this invention is to permit the construction of a power driving tool which, by means obtained from said pneumatically driven hammer, has less depth than comparably powered piston driving devices.
Another object of this invention is the provision, by means described above, of a driving device which has less weight than comparably powered piston driving devices.
Another object of this invention is the provision of means whereby many said driving operations can be incorporated in a small tool package.
Another object of this invention is the provision of means whereby the device can index a fastener.